Contactless blood pressure monitoring of a patient

ABSTRACT

Contactless blood pressure monitoring, includes: illuminating a blood vessel of a patient with infrared (‘IR’) light; receiving, by an IR camera through a polarizing filter, IR light reflected by the patient; capturing at a time based on a heartrate of the patient, a first IR image of the blood vessel of the patient when the blood vessel is distended; determining, from the first image, a maximum diameter of the blood vessel; capturing at a time based on the heartrate of the patient, a second IR image of the blood vessel of the patient when the blood vessel is contracted; determining, from the second IR image, a minimum diameter of the blood vessel; and calculating blood pressure of the patient in dependence upon the maximum and minimum diameters of the blood vessel.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of and claims priorityfrom U.S. patent application Ser. No. 15/349,428, filed on Nov. 11,2016.

BACKGROUND Field of the Invention

The field of the invention is data processing, or, more specifically,methods, apparatus, and products for contactless blood pressuremonitoring of a patient.

Description Of Related Art

Current medical technology for gathering various blood related metricssuch as blood pressure, heart rate, and blood flow rate, generallyrequire physical contact between a patient and a medical device. Forexample, blood pressure is generally measured with a sphygmomanometer(also called a blood pressure meter or monitor) that includes aninflatable cuff. Such a cuff constricts the blood flow through apatient's veins when inflated and contracts in a controlled manner tomeasure the blood pressure of the vein when constricted and whenunconstricted. Such a constriction may be uncomfortable for manypatients.

SUMMARY

Methods, apparatus and products for A method of contactless bloodpressure monitoring of a patient are disclosed in this specification.Such contactless blood pressure monitoring includes: illuminating, by ablood pressure monitoring system, a blood vessel of a patient withinfrared (‘IR’) light; receiving, by an IR camera of the blood pressuremonitoring system through a polarizing filter, IR light reflected by thepatient; capturing at a time based on a heartrate of the patient, by theIR camera of the blood pressure monitoring system, a first IR image ofthe blood vessel of the patient when the blood vessel is distended;determining, by the blood pressure monitoring system from the firstimage, a maximum diameter of the blood vessel; capturing at a time basedon the heartrate of the patient, by IR camera of the contactless bloodpressure monitoring system, a second IR image of the blood vessel of thepatient when the blood vessel is contracted; determining, by the bloodpressure monitoring system from the second IR image, a minimum diameterof the blood vessel; and calculating, by the blood pressure monitoringsystem, blood pressure of the patient in dependence upon the maximum andminimum diameters of the blood vessel.

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescriptions of exemplary embodiments of the invention as illustrated inthe accompanying drawings wherein like reference numbers generallyrepresent like parts of exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 sets forth a block diagram of a system configured for contactlessblood pressure monitoring of a patient according to embodiments of thepresent invention.

FIG. 2 sets forth a flow chart illustrating an exemplary method forcontactless blood pressure monitoring of a patient according toembodiments of the present invention.

FIG. 3 sets forth a diagram of a blood vessel of a patient.

FIG. 4 sets forth a flow chart illustrating a further exemplary methodfor contactless blood pressure monitoring of a patient according toembodiments of the present invention that includes calculating theheartrate of the patient.

FIG. 5 sets forth a flow chart illustrating a further exemplary methodfor contactless blood pressure monitoring of a patient according toembodiments of the present invention that includes calculating theheartrate of the patient.

FIG. 6 sets forth another diagram of a blood vessel of a patient.

FIG. 7 sets forth a flow chart illustrating a further exemplary methodfor contactless blood pressure monitoring of a patient according toembodiments of the present invention that includes calculating theheartrate of the patient.

DETAILED DESCRIPTION

Exemplary methods, apparatus, and products for contactless bloodpressure monitoring of a patient in accordance with the presentinvention are described with reference to the accompanying drawings,beginning with FIG. 1. FIG. 1 sets forth a block diagram of a systemconfigured for contactless blood pressure monitoring of a patientaccording to embodiments of the present invention. The system of FIG. 1includes an example of a contactless blood pressure monitoring systemaccording to various embodiments of the present invention. Such a bloodpressure monitoring system may be implemented with automated computingmachinery in the form of a computer (152), a camera (104), and a severallight sources (106, 102).

The example computer (152) of FIG. 1 includes at least one computerprocessor (156) or ‘CPU’ as well as random access memory (168) (‘RAM’)which is connected through a high speed memory bus (166) and bus adapter(158) to processor (156) and to other components of the computer (152).

Stored in RAM (168) is a blood pressure monitoring module (126), amodule of computer program instructions for contactless blood pressuremonitoring in accordance with embodiments of the present invention. Tothat end, the blood pressure monitoring module (126) may illuminate,through use of the IR light source (102), one or more blood vessels of apatient (100) with IR light. In some embodiments of the presentinvention, illuminating the patient (100) with IR light may includeilluminating the patient's face. The face includes many blood vessels inthe form of veins, capillaries, and so on as will occur to readers ofskill in the art. A blood vessel, as the term is used in thisspecification, may refer to any or all of: a vein, a capillary, and anartery.

The blood pressure monitoring module (126) may also receive, by an IRcamera (104) through a polarizing filter (108), IR light reflected (110)by the patient (100). The camera (104) in the example of FIG. 1 may beimplemented in a variety of ways. For example, the camera may be adigital video camera configured to capture IR light, visible light, orboth. In some embodiments, multiple cameras may be implemented. In suchan embodiment, one camera may be an RGBa camera and another an IRcamera. A polarizing filter generally blocks polarized light frompassing through the filter. Various types of polarizing filters maybeutilized in the example system of FIG. 1 such as a linear polarizer, acircular polarizer, or a combination of the two.

The blood pressure monitoring module (126), through the camera (104) mayalso capture at a time based on a heartrate of the patient a first IRimage of the blood vessel of the patient when the blood vessel isdistended—that is, fully dilated. Readers of skill in the art willrecognize that such a ‘capture’ of an image may be carried out bycapturing many images, by capturing a stream of frames in a digitalvideo for example, and sampling the image data from the many images. Infact, each time the term ‘capture’ is used in this specification,readers of skill in the art will recognize that the term may refer tocapturing many images and sampling the image data from those images.

A heart beat occurs in a cardiac cycle. The cardiac cycle begins insystole in which the ventricles of the heart contract, pumping blood outto the cardiovascular network. The cycle continues with an interveningpause, finally followed by diastole in which the ventricles of the heartrelax. Responsive to the systole period in the cardiac cycle vesselsexperience increased pressure and thus distend. At this point, based ona known or calculated heart rate (described below), the blood pressuremonitoring module captures an IR image of the blood vessel. Readers ofskill in the art will recognize that capturing an IR image of a bloodvessel refers generally to capturing an image of a portion of thevessel, rather than the entire vessel.

From the first IR image, the blood pressure monitoring module (126) maydetermine a maximum diameter of the blood vessel. The diameter may becalculated based on image processing of the image where edges of thevessels may be identified and the distance between the edges at thepoint of maximum distension may be calculated in a variety of ways.

The blood pressure monitoring module (126), through the camera (104),may then capture at a time based on the heartrate of the patient, asecond IR image of the blood vessel of the patient when the blood vesselis contracted. The same portion of the blood vessel previously capturedin an IR image when at full distension may be captured when the vesselis fully contracted, that is during the diastole period of the cardiaccycle of the heart. Likewise, the blood pressure monitoring maydetermine, from the second IR image, a minimum diameter of the bloodvessel.

From these maximum diameters, the blood pressure monitoring module maythen calculate blood pressure of the patient. Blood pressure isgenerally directly proportional to the product of the blood flow rateand total peripheral resistance. Total peripheral resistance is highlyvariable based on the radius of the blood vessel. The blood pressuremonitoring module (126) may calculate blood pressure in a variety ofways. Blood pressure generally is measured at diastole and at systole.In some embodiments, the blood pressure monitoring module (126) maycalculate the diastolic blood pressure by assuming or calculating ablood flow rate, approximating the total peripheral resistance based onthe maximum diameter, and calculating the product of the two. The bloodpressure monitoring module (126) may also calculate the systolic bloodpressure by assuming or calculating a blood flow rate, approximating thetotal peripheral resistance based on the minimum diameter, andcalculating the product of the two. Readers of skill in the art willrecognize that this is but one way, among many possible ways, tocalculate blood pressure from the maximum and minimum diameters of ablood vessel. Each such possible way is well within the scope of thepresent invention.

Readers of skill in the art will recognize the blood pressure monitoringsystem depicted in FIG. 1, including the computer (152), the camera(104), and the light sources (102, 106) may be implemented in a varietyof different manners. The system may be implemented in a kiosk in whicha user may approach the kiosk, request blood pressure monitoring throughuse of user input devices, and receive on a display (180) the results ofthe monitoring. Readers will also recognize that such monitoring may bedynamic and continuous. Many cameras, for example, may be configured tocapture 24 frames each second, and the capture of IR images followed,determination of maximum and minimum vessel diameters, and calculationof blood pressure may be carried out many times in a short period oftime.

Also stored in RAM (168) is an operating system (154). Operating systemsuseful in computers configured for contactless blood pressure monitoringof a patient according to embodiments of the present invention includeUNIX™, Linux™, Microsoft Windows™, AIX™ IBM's i™ operating system, andothers as will occur to those of skill in the art. The operating system(154) and blood pressure monitoring module (126) in the example of FIG.1 are shown in RAM (168), but many components of such software typicallyare stored in non-volatile memory also, such as, for example, on a diskdrive (170).

The computer (152) of FIG. 1 includes disk drive adapter (172) coupledthrough expansion bus (160) and bus adapter (158) to processor (156) andother components of the computer (152). Disk drive adapter (172)connects non-volatile data storage to the computer (152) in the form ofdisk drive (170). Disk drive adapters useful in computers configured forcontactless blood pressure monitoring of a patient according toembodiments of the present invention include Integrated DriveElectronics (‘IDE’) adapters, Small Computer System Interface (‘SCSI’)adapters, and others as will occur to those of skill in the art.Non-volatile computer memory also may be implemented for as an opticaldisk drive, electrically erasable programmable read-only memory(so-called ‘EEPROM’ or ‘Flash’ memory), RAM drives, and so on, as willoccur to those of skill in the art.

The example computer (152) of FIG. 1 includes one or more input/output(‘I/O’) adapters (178). I/O adapters implement user-orientedinput/output through, for example, software drivers and computerhardware for controlling output to display devices such as computerdisplay screens, as well as user input from user input devices (181)such as keyboards and mice. The example computer (152) of FIG. 1includes a video adapter (209), which is an example of an I/O adapterspecially designed for graphic output to a display device (180) such asa display screen or computer monitor. Video adapter (209) is connectedto processor (156) through a high speed video bus (164), bus adapter(158), and the front side bus (162), which is also a high speed bus.

The exemplary computer (152) of FIG. 1 includes a communications adapter(167) for data communications with other computers and for datacommunications with a data communications network (not shown here). Suchdata communications may be carried out serially through RS-232connections, through external buses such as a Universal Serial Bus(‘USB’), through data communications networks such as IP datacommunications networks, and in other ways as will occur to those ofskill in the art. Communications adapters implement the hardware levelof data communications through which one computer sends datacommunications to another computer, directly or through a datacommunications network. Examples of communications adapters useful incomputers configured for contactless blood pressure monitoring of apatient according to embodiments of the present invention include modemsfor wired dial-up communications, Ethernet (IEEE 802.3) adapters forwired data communications, and 802.11 adapters for wireless datacommunications.

The arrangement of computer components, cameras, and light sourcesmaking up the exemplary system illustrated in FIG. 1 are forexplanation, not for limitation. Data processing systems usefulaccording to various embodiments of the present invention may includeadditional servers, routers, other devices, and peer-to-peerarchitectures, not shown in FIG. 1, as will occur to those of skill inthe art. Networks in such data processing systems may support many datacommunications protocols, including for example TCP (TransmissionControl Protocol), IP (Internet Protocol), HTTP (HyperText TransferProtocol), WAP (Wireless Access Protocol), HDTP (Handheld DeviceTransport Protocol), and others as will occur to those of skill in theart. Various embodiments of the present invention may be implemented ona variety of hardware platforms in addition to those illustrated in FIG.1.

For further explanation, FIG. 2 sets forth a flow chart illustrating anexemplary method for contactless blood pressure monitoring of a patientaccording to embodiments of the present invention. The example method ofFIG. 2 may be carried out by a system similar to that depicted in theexample of FIG. 1.

The method of FIG. 2 includes illuminating (202), by a blood pressuremonitoring system, a blood vessel of a patient with IR light.Illuminating (202) a blood vessel (or many blood vessels) may be carriedout by projecting IR light, from an IR light source, on the face orother exposed skin of a patient.

The method of FIG. 2 also includes receiving (204), by an IR camera ofthe blood pressure monitoring system through a polarizing filter, IRlight reflected by the patient. The IR camera may include one or morelens filters to block incoming light in the visible light spectrum whileallowing IR light to reach a CCD (charged-couple device) sensor or CMOS(complementary metal oxide semiconductor) sensor.

The method of FIG. 2 also includes capturing (206) at a time based on aheartrate of the patient, by the IR camera of the blood pressuremonitoring system, a first IR image (208) of the blood vessel of thepatient when the blood vessel is distended. In an embodiment when the IRcamera is a 24 FPS (frame per second) digital video camera, capturing afirst IR image may be carried out by storing a stream of frames for aperiod of time and identifying one, based on the heartrate, thatincludes the vessel at full distension.

The method of FIG. 2 also includes determining (210), by the bloodpressure monitoring system from the first image (208), a maximumdiameter (220) of the blood vessel. The diameter may be calculatedthrough image processing in which edge detection is employed to identifythe edges of the vessel. The distance between two points on oppositedetected edges may be determined as the diameter.

The method of FIG. 2 also includes capturing (212) at a time based onthe heartrate of the patient, by IR camera of the contactless bloodpressure monitoring system, a second IR image (214) of the blood vesselof the patient when the blood vessel is contracted. The method of FIG. 2also includes determining, by the blood pressure monitoring system fromthe second IR image, a minimum diameter (218) of the blood vessel.

The method of FIG. 2 also includes calculating (224), by the bloodpressure monitoring system, blood pressure of the patient in dependenceupon the maximum and minimum diameters of the blood vessel. Calculating(224) blood pressure may be carried out by calculating both a diastolicand a systolic pressure and such calculation may be carried out in avariety of ways. In some embodiments, each diameter (220, 218) may beused to determine or assume a total peripheral resistance. With a knownor calculated blood flow rate, calculating diastolic and systolic bloodpressure may be carried out by determining the product of the totalperipheral resistance (at each diameter) and the blood flow rate. Aftercalculation, the blood pressure may be displayed or otherwise providedto the patient or electronically provided (via email, or othermessaging) to a physician.

For further explanation, FIG. 3 sets forth a diagram of a blood vesselof a patient. One vessel (202) of the patient is blown up for clarity.The vessel is shown at two times: to in which the heart is a diastoleperiod and the vessel is contracting and ti in which the heart is in thesystole period and the vessel is distended. At each time, while thepatient is illuminated with IR light, the blood pressure monitoringsystem may capture an IR image that includes a point of interest (206).From the images the blood pressure monitoring system may determine, atthe point of interest at to, the minimum (218) diameter and at the pointof interest at ti, the maximum diameter (220).

As mentioned above, the heartrate of the patient, which may be used todetermine the timing of capturing the IR images of the patient's bloodvessel at distension and contraction, may be assumed or otherwisecalculated. To that end, the method of FIG. 4 sets forth a flow chartillustrating a further exemplary method for contactless blood pressuremonitoring of a patient according to embodiments of the presentinvention that includes calculating the heartrate of the patient.

The method of FIG. 4 is similar to the method of FIG. 2, in that themethod of FIG. 4 also includes illuminating (202) a blood vessel of apatient with infrared IR light; receiving (204) IR light reflected bythe patient; capturing (206) at a time based on a heartrate of thepatient a first IR image (208) of the blood vessel of the patient whenthe blood vessel is distended; determining (210) a maximum diameter(220) of the blood vessel; capturing (212) at a time based on theheartrate of the patient a second IR image (214) of the blood vessel ofthe patient when the blood vessel is contracted; determining (216) aminimum diameter (220) of the blood vessel; and calculating (224) bloodpressure (226) of the patient in dependence upon the maximum and minimumdiameters of the blood vessel.

The method of FIG. 4 differs from the method of FIG. 2, however, in thatthe method of FIG. 4 includes calculating (402) the heartrate of thepatient. In the method of FIG. 4, calculating (402) the heartrate of thepatient is carried out by: illuminating (404) the patient with IR lightand visible light; capturing (406) a series of RGBa (‘Red, Green, Blue,Alpha’) images while the patient is illuminated with the IR light;identifying (408) from the RGBa images, maximum RGBa intensity values;and determining (410), as the patient's heartbeat, a frequency ofrecurring maximum RGBa intensity values over a period of time.

When the heart beats, blood flows more quickly through the vessel, andthe vessel distends. Upon doing so, the color of the vessel varies. Thevariation is periodic (or semi-periodic) based on the regular periodicheart beat of the patient. As such, the periodicity, or frequency, ofthe variance of the color may be utilized as the heartbeat.

Each image in the series of images includes a plurality of pixels. Eachpixel is defined by intensity values for red, intensity values forgreen, and intensity values for blue. As the color of the vessel varies,the pixel in each image varies in intensity values. As such, identifying(408) maximum RGBa intensity values from the images may be carried outin a variety of ways. In one example, the blood pressure monitoringsystem may calculate for each of a number of pixels and for each color,average intensity values. The blood pressure monitoring may thencalculate a score based on the sum of the average intensity values ofthe colors and compare those sums to sums of other images in the series.Those having the highest intensity values within a range of one anothermay be determined to be images containing maximum RGBa intensity values.

Not only may the heartrate of the patient be calculated for later use incapturing IR images for blood pressure calculation, but the heartratemay be a diagnostic provided to the patient or doctor.

For further explanation, the method of FIG. 5 sets forth a flow chartillustrating a further exemplary method for contactless blood pressuremonitoring of a patient according to embodiments of the presentinvention that includes calculating the heartrate of the patient. Themethod of FIG. 5 is similar to the method of FIG. 2, in that the methodof FIG. 5 also includes illuminating (202) a blood vessel of a patientwith infrared IR light; receiving (204) IR light reflected by thepatient; capturing (206) at a time based on a heartrate of the patient afirst IR image (208) of the blood vessel of the patient when the bloodvessel is distended; determining (210) a maximum diameter (220) of theblood vessel; capturing (212) at a time based on the heartrate of thepatient a second IR image (214) of the blood vessel of the patient whenthe blood vessel is contracted; determining (216) a minimum diameter(220) of the blood vessel; and calculating (224) blood pressure (226) ofthe patient in dependence upon the maximum and minimum diameters of theblood vessel.

The method of FIG. 5 differs from the method of FIG. 2, however, in thatthe method of FIG. 5 includes calculating (502) a blood flow rate of thepatient. In the method of FIG. 5, calculating the blood flow rate of thepatient is carried out by: illuminating (504) the patient with IR lightand visible light; capturing (506) a series of RGBa images while thepatient is illuminated with the IR light; identifying (508), from theseries of RGBa images, a first image of a blood vessel when an upstreamlocation in the blood vessel is distended and a downstream location isnot distended; identifying (510), from the series of RGBa images, asecond image of the blood vessel when the downstream location isdistended; calculating (512) a difference in time between the capture ofthe first and second image; and calculating (514), based on thedifference in time, a blood flow rate.

Blood flow rate may be determined by the time it takes for blood to flowfrom one point, an upstream location, to a second point in the bloodvessel, a downstream location. The blood pressure monitoring system maybe configured or calculate a distance between the upstream anddownstream location, then identify in the images when the blood flowsthrough each location. The blood pressure monitoring may identify a timewhen the blood flows through a location as the time at which the vesseldistends at that location. That is, at a first time, the blood flowsthrough the upstream location, distending the vessel at that location.Later, at a second time, the blood flows through the downstream locationdistending the vessel at that location. The ratio of the difference intimes between the two distensions and the distance between the twolocations is the blood flow rate.

As mentioned above, the blood flow rate may be utilized in thecalculation of blood pressure. To that end, calculating (224) bloodpressure of the patient may be carried out by calculating (516) bloodpressure of the patient in dependence upon the blood flow rate and themaximum and minimum diameters of the blood vessel.

For further explanation, FIG. 6 sets forth another diagram of a vesselof a patient. One vessel (602) of the patient is blown up for clarity.The vessel (602) is shown at two times: to in which an upstream location(605) is distended (620) due to blood flow (618) and ti in which thedownstream location (606) of the vessel is distended due to blood flow.Over a period of time, while the patient is illuminated with IR light,the blood pressure monitoring system may capture a series of IR imagesthat includes the vessel at to and ti. From the images the bloodpressure monitoring system may identify the image containing theupstream location distended and the image containing the downstreamlocation distended. The blood pressure monitoring system may thencalculate or determine the time between the capture of those images.Finally, the blood pressure monitoring system may divide the differencein time by the distance between the two locations (605, 606).

For further explanation, the method of FIG. 7 sets forth a flow chartillustrating a further exemplary method for contactless blood pressuremonitoring of a patient according to embodiments of the presentinvention that includes calculating the heartrate of the patient. Themethod of FIG. 7 is similar to the method of FIG. 2, in that the methodof FIG. 7 also includes illuminating (202) a blood vessel of a patientwith infrared IR light; receiving (204) IR light reflected by thepatient; capturing (206) at a time based on a heartrate of the patient afirst IR image (208) of the blood vessel of the patient when the bloodvessel is distended; determining (210) a maximum diameter (220) of theblood vessel; capturing (212) at a time based on the heartrate of thepatient a second IR image (214) of the blood vessel of the patient whenthe blood vessel is contracted; determining (216) a minimum diameter(220) of the blood vessel; and calculating (224) blood pressure (226) ofthe patient in dependence upon the maximum and minimum diameters of theblood vessel.

The method of FIG. 7 differs from the method of FIG. 2 in that in themethod of FIG. 7, calculating (224) the blood pressure (226) of thepatient also includes reducing (702), by a source separation algorithm,influence of background radiation. In some embodiments, stray, ambient,or background radiation may reach the IR camera of the blood pressuremonitoring system. Such background radiation may include IR and RGBasources other than those controlled by the blood pressure monitoringsystem. To that end, a source separation algorithm may be applied tofilter some or all of the background radiation from the image dataprovided by the camera. A source separation algorithm attempts toidentify distinct components that have been combined and remove all butthe desired component. To aid the source separation algorithm, thecamera may capture images when no patient is present to identifybackground radiation that is present and likely to be captured by thecamera. Then, when applying the source separation algorithm thepreviously identified background radiation may be taken into accountwhen removing components that may be undesirable for blood pressuremonitoring calculations. Further, multiple known light sources may beprojected on the user to limit the amount of stray radiation that can bereceived by the camera.

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

It will be understood from the foregoing description that modificationsand changes may be made in various embodiments of the present inventionwithout departing from its true spirit. The descriptions in thisspecification are for purposes of illustration only and are not to beconstrued in a limiting sense. The scope of the present invention islimited only by the language of the following claims.

1. A method of contactless blood pressure monitoring of a patient, themethod comprising: illuminating, by a blood pressure monitoring system,a blood vessel of a patient with infrared (‘IR’) light, wherein theblood pressure monitoring system comprises an IR camera, a polarizingfilter, and a computer processor; receiving, by the IR camera of theblood pressure monitoring system through the polarizing filter, IR lightreflected by the patient; capturing at a time based on a heartrate ofthe patient, by the IR camera of the blood pressure monitoring system, afirst IR image of the blood vessel of the patient when the blood vesselis distended; determining, by the blood pressure monitoring system fromthe first IR image, a maximum diameter of the blood vessel, whereindetermining, by the blood pressure monitoring system from the first IRimage, the maximum diameter of the blood vessel comprises measuring,from the IR image, a distance between points on the blood vessel;capturing at a time based on the heartrate of the patient, by the IRcamera of the contactless blood pressure monitoring system, a second IRimage of the blood vessel of the patient when the blood vessel iscontracted; determining, by the blood pressure monitoring system fromthe second IR image, a minimum diameter of the blood vessel;calculating, by the computer processor of the blood pressure monitoringsystem, blood pressure of the patient in dependence upon the maximum andminimum diameters of the blood vessel; and providing, by the bloodpressure monitoring system, the calculated blood pressure to oneselected from a group consisting of the patient and a physician.
 2. Themethod of claim 1 further comprising calculating the heartrate of thepatient including: illuminating the patient with IR light and visiblelight; capturing a series of RGBa (‘Red, Green, Blue, Alpha’) imageswhile the patient is illuminated with the IR light; identifying from theRGBa images, maximum RGBa intensity values; and determining, as thepatient's heartrate, a frequency of recurring maximum RGBa intensityvalues over a period of time.
 3. The method of claim 1 further comprisescalculating a blood flow rate of the patient, including: illuminatingthe patient with IR light and visible light; capturing a series of RGBa(‘Red, Green, Blue, Alpha’) images while the patient is illuminated withthe IR light; identifying, from the series of RGBa images, a first imageof a blood vessel when an upstream location in the blood vessel isdistended and a downstream location is not distended; identifying, fromthe series of RGBa images, a second image of the blood vessel when thedownstream location is distended; calculating a difference in timebetween the capture of the first and second image; and calculating,based on the difference in time, a blood flow rate.
 4. The method ofclaim 3 wherein calculating blood pressure of the patient furthercomprises calculating blood pressure of the patient in dependence uponthe blood flow rate and the maximum and minimum diameters of the bloodvessel.
 5. The method of claim 1 wherein calculating the blood pressureof the patient further comprises reducing, by a source separationalgorithm, influence of background radiation.
 6. The method of claim 1wherein illuminating a blood vessel of the patient with IR light furthercomprises illuminating the face of the patient with IR light.
 7. Themethod of claim 1, wherein the calculation of blood pressure is updatedperiodically while the patient is present.
 8. An apparatus forcontactless blood pressure monitoring of a patient, the apparatuscomprising a blood pressure monitoring system comprising: a computerprocessor, an IR camera, a polarizing filter, and a computer memoryoperatively coupled to the computer processor, wherein the computermemory has disposed within it computer program instructions that, whenexecuted by the computer processor, cause the apparatus to carry out thesteps of: illuminating, by the blood pressure monitoring system, a bloodvessel of a patient with infrared (‘IR’) light; receiving, by the IRcamera of the blood pressure monitoring system through the polarizingfilter, IR light reflected by the patient; capturing at a time based ona heartrate of the patient, by the IR camera of the blood pressuremonitoring system, a first IR image of the blood vessel of the patientwhen the blood vessel is distended; determining, by the blood pressuremonitoring system from the first IR image, a maximum diameter of theblood vessel, wherein determining, by the blood pressure monitoringsystem from the first IR image, the maximum diameter of the blood vesselcomprises measuring, from the IR image, a distance between points on theblood vessel; capturing at a time based on the heartrate of the patient,by the IR camera of the contactless blood pressure monitoring system, asecond IR image of the blood vessel of the patient when the blood vesselis contracted; determining, by the blood pressure monitoring system fromthe second IR image, a minimum diameter of the blood vessel;calculating, by the computer processor of the blood pressure monitoringsystem, blood pressure of the patient in dependence upon the maximum andminimum diameters of the blood vessel; and providing, by the bloodpressure monitoring system, the calculated blood pressure to oneselected from a group consisting of the patient and a physician.
 9. Theapparatus of claim 8 wherein the computer memory has disposed within itfurther computer program instructions that, when executed by thecomputer processor, cause the apparatus to carry out the step ofcalculating the heartrate of the patient including: illuminating thepatient with IR light and visible light; capturing a series of RGBa(‘Red, Green, Blue, Alpha’) images while the patient is illuminated withthe IR light; identifying from the RGBa images, maximum RGBa intensityvalues; and determining, as the patient's heartrate, a frequency ofrecurring maximum RGBa intensity values over a period of time.
 10. Theapparatus of claim 8 wherein the computer memory has disposed within itfurther computer program instructions that, when executed by thecomputer processor, cause the apparatus to carry out the step ofcalculating a blood flow rate of the patient, including: illuminatingthe patient with IR light and visible light; capturing a series of RGBa(‘Red, Green, Blue, Alpha’) images while the patient is illuminated withthe IR light; identifying, from the series of RGBa images, a first imageof a blood vessel when an upstream location in the blood vessel isdistended and a downstream location is not distended; identifying, fromthe series of RGBa images, a second image of the blood vessel when thedownstream location is distended; calculating a difference in timebetween the capture of the first and second image; and calculating,based on the difference in time, a blood flow rate.
 11. The apparatus ofclaim 10 wherein calculating blood pressure of the patient furthercomprises calculating blood pressure of the patient in dependence uponthe blood flow rate and the maximum and minimum diameters of the bloodvessel.
 12. The apparatus of claim 8 wherein calculating the bloodpressure of the patient further comprises reducing, by a sourceseparation algorithm, influence of background radiation.
 13. Theapparatus of claim 8 wherein illuminating a blood vessel of the patientwith IR light further comprises illuminating the face of the patientwith IR light.
 14. The apparatus of claim 8, wherein the calculation ofblood pressure is updated periodically while the patient is present. 15.A computer program product for contactless blood pressure monitoring ofa patient, the computer program product disposed upon a non-transitorycomputer readable medium, the computer program product comprisingcomputer program instructions that, when executed by a computerprocessor of a blood pressure monitoring system, cause the bloodpressure monitoring system to carry out the steps of: illuminating, bythe blood pressure monitoring system, a blood vessel of a patient withinfrared (‘IR’) light, wherein the blood pressure monitoring systemcomprises an IR camera and a polarizing filter; receiving, by the IRcamera of the blood pressure monitoring system through the polarizingfilter, IR light reflected by the patient; capturing at a time based ona heartrate of the patient, by the IR camera of the blood pressuremonitoring system, a first IR image of the blood vessel of the patientwhen the blood vessel is distended; determining, by the blood pressuremonitoring system from the first IR image, a maximum diameter of theblood vessel, wherein determining, by the blood pressure monitoringsystem from the first IR image, the maximum diameter of the blood vesselcomprises measuring, from the IR image, a distance between points on theblood vessel; capturing at a time based on the heartrate of the patient,by the IR camera of the contactless blood pressure monitoring system, asecond IR image of the blood vessel of the patient when the blood vesselis contracted; determining, by the blood pressure monitoring system fromthe second IR image, a minimum diameter of the blood vessel;calculating, by the computer processor of the blood pressure monitoringsystem, blood pressure of the patient in dependence upon the maximum andminimum diameters of the blood vessel; and providing, by the bloodpressure monitoring system, the calculated blood pressure to oneselected from a group consisting of the patient and a physician.
 16. Thecomputer program product of claim 15 further comprising computer programinstructions that, when executed, cause the computer to carry out thestep of calculating the heartrate of the patient including: illuminatingthe patient with IR light and visible light; capturing a series of RGBa(‘Red, Green, Blue, Alpha’) images while the patient is illuminated withthe IR light; identifying from the RGBa images, maximum RGBa intensityvalues; and determining, as the patient's heartrate, a frequency ofrecurring maximum RGBa intensity values over a period of time.
 17. Thecomputer program product of claim 15 further comprising computer programinstructions that, when executed, cause the computer to carry out thestep of calculating a blood flow rate of the patient, including:illuminating the patient with IR light and visible light; capturing aseries of RGBa (‘Red, Green, Blue, Alpha’) images while the patient isilluminated with the IR light; identifying, from the series of RGBaimages, a first image of a blood vessel when an upstream location in theblood vessel is distended and a downstream location is not distended;identifying, from the series of RGBa images, a second image of the bloodvessel when the downstream location is distended; calculating adifference in time between the capture of the first and second image;and calculating, based on the difference in time, a blood flow rate. 18.The computer program product of claim 17 wherein calculating bloodpressure of the patient further comprises calculating blood pressure ofthe patient in dependence upon the blood flow rate and the maximum andminimum diameters of the blood vessel.
 19. The computer program productof claim 15 wherein calculating the blood pressure of the patientfurther comprises reducing, by a source separation algorithm, influenceof background radiation.
 20. The computer program product of claim 15wherein illuminating a blood vessel of the patient with IR light furthercomprises illuminating the face of the patient with IR light.
 21. Thecomputer program product of claim 15, wherein the calculation of bloodpressure is updated periodically while the patient is present.
 22. Thecomputer program product of claim 15 wherein the blood vessel comprisesa capillary.